Downhole Ball Dropping Systems and Methods with Redundant Ball Dropping Capability

ABSTRACT

A downhole ball dropping system operable to be positioned in a well. The system includes a tool string having a flow path. First and second ball dropper assemblies are interconnected in the tool string. The first ball dropper assembly releasably retains a first ball and the second ball dropper assembly releasably retains a second ball. A sensor is operable to detect deployment of the first ball and is operable to generate a signal to prevent release of the second ball from the second ball dropper assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119 of the filing date of International Application No. PCT/US2013/058952, filed Sep. 10, 2013.

TECHNICAL FIELD OF THE DISCLOSURE

This disclosure relates, in general, to equipment utilized in conjunction with operations performed in relation to subterranean wells and, in particular, to downhole systems and methods for the deployment and use of one or more balls for the actuation of downhole tools.

BACKGROUND OF THE DISCLOSURE

Without limiting the scope of the present disclosure, its background is described with reference to actuating a downhole tool responsive to tubing pressure applied against a ball disposed in a ball seat, as an example.

It is well known in the subterranean well drilling and completion art to locate a downhole tool string within a casing, liner or production tubing to perform desired operations. Such a tool string may incorporate a variety of tools including sliding sleeves, circulating subs, packers and the like. Once the tool string is properly positioned downhole, actuation of one or more of the downhole tools in the string may be desired. One method to actuate such downhole tools involves deployment of a ball operable to travel down the tool string and engage a ball seat within the downhole tool or an associated setting tool. Thereafter, tubing pressure may be applied to actuate the downhole tool. For example, in the case of a packer, the ball may engage a seat in a packer setting tool. The fluid pressure is then increased above a certain threshold to actuate the packer setting tool, which in turn sets the packer to engage the casing, liner or production tubing.

Typically, the ball used to actuate the downhole tool is deployed from the surface. The ball must then be gravity feed or pumped through the pipe string until it reaches the downhole seat. It has been found, however, that although such a method works in many circumstances, there are several drawbacks to this method. For example, deployment of a ball from the surface is a time-consuming and costly process. In addition, deployment of a ball from the surface may result in the ball becoming stuck or lost in the pipe string or otherwise never making it to the downhole seat. Further, to ensure that the ball can be displaced from the surface to the downhole seat, all of the tools and components in the pipe string above the downhole seat must be free from restrictions that would prevent the ball from passing therethrough.

Accordingly, a need has arisen for an improved system and method for deploying a ball for engagement with a ball seat to enable actuation of a downhole tool. A need has also arisen for such an improved system and method for deploying a ball that does not require gravity feeding or pumping the ball from the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description of the disclosure along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

FIGS. 1A-1D are schematic illustrations of a downhole ball dropping system according to an embodiment of the present disclosure in various operating configurations;

FIGS. 2A-2D are schematic illustrations of a downhole ball dropping system according to an embodiment of the present disclosure in various operating configurations;

FIG. 3 is a process flow diagram of a downhole ball dropping method according to an embodiment of the present disclosure;

FIGS. 4A-4M are schematic illustrations of various embodiments of actuators that are operable for use in downhole ball dropping systems according to the present disclosure; and

FIG. 5 is a perspective illustration of a ball release mechanism for use in a downhole ball dropping system according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

While various system, method and other embodiments are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative, and do not delimit the scope of the present disclosure.

In one aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. First and second ball dropper assemblies are interconnected in the tool string. The first ball dropper assembly releasably retains a first ball and the second ball dropper assembly releasably retains a second ball. A sensor is operable to detect deployment of the first ball and is operable to generate a signal to prevent release of the second ball from the second ball dropper assembly.

In one embodiment, the second ball dropper assembly may be positioned downhole of the first ball dropper assembly. In another embodiment, the second ball dropper assembly may be circumferentially positioned relative to the first ball dropper assembly. In some embodiments, the sensor may be operable to detect the first ball passing through the flow path after release thereof by the first ball dropper assembly. For example, the first ball may be a magnetic device and the sensor may detect a change in a magnetic field. Alternatively, the first ball may include an RFID tag and the sensor may be an RFID reader. In certain embodiments, the sensor may be operable to detect release of the first ball from first ball dropper assembly.

In another aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal to the first ball dropper assembly to release the first ball; detecting deployment of the first ball with a downhole sensor; and generating a deactivation signal from the downhole sensor to prevent release of the second ball from the second ball dropper assembly.

The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting the first ball passing through the flow path after release thereof by the first ball dropper assembly; detecting a change in a magnetic field; detecting an RFID tag; detecting release of the first ball from the first ball dropper assembly; and/or sending a deployment signal from the downhole sensor to at least one of a surface controller and a downhole component.

In a further aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. A first ball dropper assembly is interconnected in the tool string. The first ball dropper assembly releasably retains a first ball. A first actuation assembly is operably associated with the first ball dropper assembly. The first actuation assembly is operated responsive to a deployment signal of a first type. A second ball dropper assembly is interconnected in the tool string. The second ball dropper assembly releasably retains a second ball. A second actuation assembly is operably associated with the second ball dropper assembly. The second actuation assembly is operated responsive to a deployment signal of a second type, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability.

In one embodiment, the second ball dropper assembly may be positioned downhole of the first ball dropper assembly. In another embodiment, the second ball dropper assembly may be circumferentially positioned relative to the first ball dropper assembly. In some embodiments, the deployment signal of the first type and the deployment signal of the second type may each be selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof.

In yet another aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal of a first type to the first ball dropper assembly to release the first ball; determining deployment of the first ball failed with a downhole sensor; and sending a deployment signal of a second type to the second ball dropper assembly to release the second ball, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability.

The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting the first ball has not passing through the flow path downhole of the first ball dropper assembly; detecting no a change in a magnetic field; detecting no RFID tag; detecting a failure to release the first ball from the first ball dropper assembly; and/or sending a deployment failure signal from the downhole sensor to at least one of a surface controller and a downhole component.

In an additional aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path and a ball dropper assembly interconnected in the tool string that releasably retains a ball; sending a deployment signal to the ball dropper assembly to release the ball; shifting a piston of a release assembly in the ball dropper assembly; pushing the ball out of the ball dropper assembly through a port with the release assembly; sensing operation of the release assembly and closing the port.

In another aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. A ball dropper assembly is interconnected in the tool string. The ball dropper assembly releasably retains a ball. An actuation assembly is operably associated with the ball dropper assembly. The actuation assembly is operated responsive to a deployment signal. A release assembly including a piston is disposed within the ball dropper assembly. A sensor is operably associated with the ball dropper assembly. Responsive to the deployment signal, the actuation assembly triggers operation of the release assembly, the release assembly pushes the ball into the flow path through a port of the ball dropper assembly, the sensor senses operation of the release assembly and the port of the ball dropper assembly is closed.

In a further aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path and a ball dropper assembly interconnected in the tool string and releasably retaining a ball; sending a deployment signal to the ball dropper assembly to release the ball; determining whether the ball deployed from the ball dropper assembly with a downhole sensor; and sending a signal from the downhole sensor to at least one of a surface controller and a downhole component indicating whether the ball deployed.

The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting whether the ball has passed through the flow path downhole of the ball dropper assembly; determining whether there is a change in a magnetic field; determining whether an RFID tag is detected; and/or detecting whether the ball was released from the ball dropper assembly.

Referring now to FIGS. 1A-1D, a tool string is being positioned in an interval of a wellbore that is generally designated 10. Tool string 12 is being run in wellbore 10 on a conveyance such as a string of jointed tubing, a string of drill pipe, a coiled tubing string or the like. Wellbore 10 extends through the various earth strata including formation 14. A casing 16 is positioned within wellbore 10 and may be secured therein by cement. Casing 16 includes a plurality of perforations 18. In the illustrated embodiment, tool string 12 has been stabbed into a sump packer 20. Tool string 12 has a central fluid flow path 22 indicated in phantom lines. In the illustrated embodiment, tool string 12 includes a sand control screen assembly 24, a ball seat assembly 26 including a ball seat 28 indicated in phantom lines, a crossover assembly 30, a packer assembly 32, a setting assembly 34 including a ball seat 36 indicated in phantom lines, a ball dropper assembly 38 including a ball 40, an actuator 42 and a sensor assembly 44, and a ball dropper assembly 46 including a ball 48, an actuator 50 and a sensor assembly 52.

Even though FIG. 1 depicts the tool string of the present disclosure as having a particular arrangement of tools, it should be understood by those skill in the art that tool strings having other arrangements of a greater number or lesser number of tools as well as tool strings having different tools requiring ball activation or ball interaction may alternatively be used. Also, even though FIG. 1 depicts the tool string of the present disclosure in a vertical wellbore, it should be understood by those skilled in the art that the tool string of the present disclosure is equally well suited for use in wellbores having other directional configurations including horizontal wellbores, deviated wellbores, slanted wells, lateral wells and the like. In such wells, in addition to or as an alternative to gravity feeding, the balls may be moved within the central fluid flow path by a moving fluid. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well and the downhole direction being toward the toe of the well. Further, even though the present description has referred to ball dropper assemblies, balls and ball seats, it is to be understood by those skilled in the art that the term “ball” as used herein will be inclusive of other flowable objects suitable for actuating downhole tools, which may or may not be spherical including, but not limited to, darts and plugs. In addition, the balls used in the systems may be made from a single material such as metal or may be formed from multiple materials such as a rubber exterior with a plastic or metal core. Alternatively or additionally, the balls may be formed from a material that dissolves over time including balls having nanosized elements therein.

Referring specifically to FIG. 1B, therein is depicted a ball dropping operation of the present disclosure. It should be noted that ball 48 may be used to perform a variety of functions in the well such as plug the tubing to allow pressure build up to actuate a piston setting tool to set a packer, plug the tubing to allow tubing pressure build up to set a hydraulic packer or otherwise actuate a tool, plug the tubing to change a flow path therethrough, for example, to direct proppant flow out into the annulus between the casing and completion hardware, change or reconfigure the flow path of the service tool for a particular operation such as an acid treatment as well as other functions known to those skilled in the art. As illustrated, ball 48 has been deployed from ball dropper assembly 46 into wellbore 10 and ball seat 36. As discussed in greater detail below, ball 48 is released from ball dropper assembly 46 responsive to operation of actuator 50. Actuator 50 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. More specifically, once tool string 10 has stabbed into sump packer 20 and it is desired to set packer assembly 32, the deployment signal is sent to actuator 50 of ball dropper assembly 46. The deployment signal causes actuation of actuator 50, which in turn causes release of ball 48 into flow path 22. Gravity, fluid flow or a combination thereof, then causes ball 48 to travel downhole and engage ball seat 36 of setting assembly 34. Once ball 48 is positioned in ball seat 36, fluid pressure acting on ball 48 may be used to set packer assembly 32.

As best seen in FIG. 1C, once packer assembly 32 has been set, additional pressure within flow path 22 may be used to cause ball 48 to pass through ball seat 36 and travel to ball seat 28 in ball seat assembly 26. In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen 24 and perforations 18 through cross over assembly 30. Thereafter, additional pressure within flow path 22 may be used to cause ball 48 to pass through ball seat 28 or return flow may be used to retrieve ball 48 to the surface or other secure location.

During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor 52 of ball dropper assembly 46 is operable to determine whether ball dropper assembly 46 has released ball 48 into flow path 22. Sensor 52 may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball 48 is located within ball dropper assembly 46, whether ball 48 has passed through a particular location of ball dropper assembly 46 or both. Regardless of the sensing means, if sensor 52 determines that ball 48 has been released into flow path 22, sensor 52 is operable to provide a signal that indicates ball 48 has been released into flow path 22. Depending upon the configuration of tool string 12, this signal may be sent to a surface controller via a wellbore telemetry system or, as illustrated, the signal may be sent directly to ball dropper assembly 38 via a wired downhole communication network 54. Alternatively, the signal may be sent from sensor 52 to ball dropper assembly 38 via a wireless downhole communication system such as via acoustic communication.

As illustrated, sensor 52 and actuator 50 of ball dropper assembly 46 and sensor 44 and actuator 42 of ball dropper assembly 38 are nodes in wired downhole communication network 54. Preferably, the signal indicating ball 48 has been released into flow path 22 is received by sensor 44 and/or actuator 42 of ball dropper assembly 38. Either or both of sensor 44 and actuator 42 may include a downhole processor operably to interpret the signal and cause deactivation of ball dropper assembly 38 such that ball 40 will not be released into flow path 22. In this embodiment, the signal from sensor 52 indicating ball 48 has been released into flow path 22 may be referred to as a deactivation signal operable to prevent release a redundant ball; namely ball 40, into flow path 22. In this manner, proper deployment of ball 48 into flow path 22 prevents a subsequent unwanted deployment of ball 40 into flow path 22.

Alternatively or additionally, sensor 44 of ball dropper assembly 38 may be operable to determine whether ball 48 of ball dropper assembly 46 has entered flow path 22 and traveled past sensor 44. Sensor 44 may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying the passing of ball 48 in flow path 22 proximate sensor 44.

In one embodiment, ball 48 may be a magnetic device that includes one or more permanent magnets disposed within or on the surface of ball 48. In this embodiment, sensor 44 may be a giant magneto-resistive (GMR) sensor, a Hall-effect sensor, conductive coils or the like. Permanent magnets can be combined with sensor 44 in order to create a magnetic field that is disturbed by ball 48. A change in the magnetic field can be detected by sensor 44 as an indication of the presence or in this case the passage of ball 48.

Sensor 44 may include electronic circuitry which determines whether the sensor has detected a particular predetermined magnetic field, or pattern or combination of magnetic fields, or other magnetic properties of ball 48. For example, the electronic circuitry could have the predetermined magnetic field(s) or other magnetic properties programmed into non-volatile memory for comparison to magnetic fields/properties detected by sensor 44. The electronic circuitry could be supplied with electrical power via an on-board battery, a downhole generator, or any other electrical power source.

In one example, the electronic circuitry could include a capacitor, wherein an electrical resonance behavior between the capacitance of the capacitor and sensor 44 changes, depending on whether ball 48 is present. In another example, the electronic circuitry could include an adaptive magnetic field that adjusts to a baseline magnetic field of the surrounding environment such as the formation, the surrounding metallic structures or the like. The electronic circuitry could determine whether the measured magnetic fields exceed the adaptive magnetic field level. In a further example, sensor 44 could comprise an inductive sensor, which can detect the presence of a metallic device by, for example, detecting a change in a magnetic field. In this case, ball 48 need not contain a magnetic element or elements, however, ball 48 can still be considered a magnetic device, in the sense that it conducts a magnetic field and produces changes in a magnetic field, which can be detected by sensor 44.

In another embodiment, ball 48 may contain an electrical circuit such as, but not limited to, a passive or active radio frequency identification (RFID) tag. In the case of ball 48 containing a passive RFID tag, sensor 44 may include a transmitter operable to transmit an alternating current electromagnetic signal into flow path 22. As ball 48 passes sensor 44, the electrical circuit of ball 44 generates an electromagnetic signal responsive to the alternating current electromagnetic signal. A receiver of sensor 44 is operable to receive the responsive signal from the electrical circuit. The passive tag circuits have no internal power source, such as a battery. They contain an electromagnetic or electronic coil that can be excited by a particular frequency of electromagnetic energy transmitted from the transmitter of sensor 44. The electromagnetic energy transmitted from the transmitter to the coil momentarily excites the coil causing the electrical circuit to transmit the contents of its buffer, such as some stored value unique to that particular tag. The transmitted information is then detected by the receiver of sensor 44.

In the case of ball 48 containing an active RFID tag, the electrical circuit carried by ball 48 generates and transmits an electromagnetic signal. In this case, sensor 44 requires only an RFID reader or receiver operable to receive the electromagnetic signal from the electrical circuit. The active tag circuits contain an internal power source, typically a long life battery. The active tag can have read and write capability, allowing its internal operating program and other information to be remotely updated or changed as required. The active tag's memory can store, for example, several kilobytes information for future recall such as serial numbers, lot numbers, build dates, expiration dates and the like. Additionally, an active tag can be designed to transmit without initiation or interrogation by a transmitter. In this manner, the active tag, under its own power and circuit design or programmed control can self-generate an identifying electromagnetic signal that is detected by the receiver of sensor 44.

Regardless of the sensing means, if sensor 44 determines that ball 48 has traveled past ball dropper assembly 38, sensor 44 is operable to provide a deactivation signal such that ball 40 will not be released into flow path 22. In this manner, proper deployment of ball 48 into flow path 22 prevents a subsequent unwanted deployment of ball 40 into flow path 22.

During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor 52 and/or sensor 44 are operable to determine whether ball 48 has been deployed from ball dropper assembly 46 into flow path 22. In the event that the active sensor or sensors determine that ball 48 has not been deployed from ball dropper assembly 46 into flow path 22, the present disclosure includes a second and redundant ball; namely ball 40, in ball dropper assembly 38 that is operable for use in actuating downhole tools such as packer assembly 32 and cross over assembly 30. In this case, ball 40 is released from ball dropper assembly 38 responsive to operation of actuator 42. Actuator 42 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator 42 and the required actuation signal for actuator 42 are different from actuator 50 and the required actuation signal for actuator 50. This is preferred as the cause of the failure of ball deployment from ball dropper assembly 46 may also cause a failure in ball dropper assembly 38 if the same type of actuator and same type of actuation signal are used.

As illustrated in FIG. 1D, if it is determine that ball 48 has not been deployed from ball dropper assembly 46 into flow path 22 by sensor 52 and/or sensor 44, then ball dropper assembly 38 is sent a deployment signal and ball 40 is deployed from ball dropper assembly 38 into flow path 22. Gravity, fluid flow or a combination thereof, then causes ball 40 to travel downhole and engage ball seat 36 of setting assembly 34. Once ball 40 is positioned in ball seat 36, fluid pressure acting on ball 40 may be used to set packer assembly 32. Thereafter, additional pressure within flow path 22 may be used to cause ball 40 to pass through ball seat 36 and travel to ball seat 28 in ball seat assembly 26. In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen 24 and perforations 18 through cross over assembly 30. Thereafter, additional pressure within flow path 22 may be used to cause ball 40 to pass through ball seat 28 or return flow may be used to retrieve ball 40 to the surface or other secure location. It is noted that tool string 12 could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path 22 in a manner similar to that of ball 40.

Referring next FIGS. 2A-2D, a tool string is being positioned in an interval of a wellbore that is generally designated 110. Tool string 112 is being run in wellbore 110 on a conveyance such as a string of jointed tubing, a string of drill pipe, a coiled tubing string or the like. Wellbore 110 extends through the various earth strata including formation 114. A casing 116 is positioned within wellbore 110 and may be secured therein by cement. Casing 116 includes a plurality of perforations 118. In the illustrated embodiment, tool string 112 has been stabbed into a sump packer 120. Tool string 112 has a central fluid flow path 122 indicated in phantom lines. In the illustrated embodiment, tool string 112 includes a sand control screen assembly 124, a ball seat assembly 126 including a ball seat 128 indicated in phantom lines, a crossover assembly 130, a packer assembly 132, a setting assembly 134 including a ball seat 136 indicated in phantom lines, a ball dropper assembly 138 including two balls 140, 141, two actuators 142, 143 and two sensor assemblies 144, 145 and a ball dropper assembly 146 including two balls 148, 149, two actuators 150, 151 and two sensor assemblies 152, 153.

Referring specifically to FIG. 2B, therein is depicted a ball dropping operation of the present disclosure. As illustrated, ball 140 from ball dropper assembly 138 has been deployed in wellbore 110 to ball seat 136. As discussed in greater detail below, ball 140 is released from ball dropper assembly 138 responsive to operation of actuator 142. Actuator 142 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof More specifically, once tool string 110 has stabbed into sump packer 120 and it is desired to set packer assembly 132, the deployment signal is sent to actuator 142 of ball dropper assembly 138. The deployment signal causes actuation of actuator 142, which in turn causes release of ball 140 into flow path 122. Gravity, fluid flow or a combination thereof, then causes ball 140 to travel downhole and engage ball seat 136 of setting assembly 134. Once ball 140 is positioned in ball seat 136, fluid pressure acting on ball 140 may be used to set packer assembly 132.

During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor 144 of ball dropper assembly 138 is operable to determine whether ball dropper assembly 138 has released ball 140 into flow path 122. Sensor 144 may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball 140 is located within ball dropper assembly 138, whether ball 140 has passed through a particular location of ball dropper assembly 138, whether ball 140 has passed through a particular location in flow path 122 or combinations thereof Regardless of the sensing means, if sensor 144 determines that ball 140 has been released into flow path 122, sensor 144 is operable to provide a signal that indicates ball 140 has been released into flow path 122. Depending upon the configuration of tool string 112, this signal may be sent to the surface, sent to another downhole tool or, as illustrated, the signal can be processed by ball dropper assembly 138 to deactivate the portion of ball dropper assembly 138 responsible for release of ball 141 into flow path 122. In this manner, proper deployment of ball 140 into flow path 122 prevents a subsequent unwanted deployment of ball 141 into flow path 122.

During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor 144 is operable to determine whether ball 140 has been deployed from ball dropper assembly 138 into flow path 122. In the event that sensor 144 determines that ball 140 has not been deployed from ball dropper assembly 138 into flow path 122, the present disclosure includes a second and redundant ball; namely ball 141 in ball dropper assembly 138 that is operable for use in actuating downhole tools such as packer assembly 132. In this case, ball 141 is released from ball dropper assembly 138 responsive to operation of actuator 143. Actuator 143 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator 143 and the required actuation signal for actuator 143 are different from actuator 142 and the required actuation signal for actuator 142. This is preferred as the cause of the failure of deployment of ball 140 may also cause a failure of deployment of ball 141 if the same type of actuator and same type of actuation signal are used.

As illustrated in FIG. 2C, if it is determine that ball 140 has not been deployed from ball dropper assembly 138 into flow path 122 by sensor 144, then ball dropper assembly 138 is sent a deployment signal and ball 141 is deployed from ball dropper assembly 138 into flow path 122. Gravity, fluid flow or a combination thereof, then causes ball 141 to travel downhole and engage ball seat 136 of setting assembly 134. Once ball 141 is positioned in ball seat 136, fluid pressure acting on ball 141 may be used to set packer assembly 132. It is noted that ball dropper assembly 138 could have one or more additional and redundant balls which could be deployed into flow path 122 in a manner similar to that of ball 141. In addition, it is noted that tool string 112 could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path 122 in a manner similar to that of ball 141. Even though ball dropper assembly 138 has been referred to as a single ball dropper assembly, ball dropper assembly 138 could alternatively be viewed as including two ball dropper assemblies, the first ball dropper assembly operable to retain and release ball 140 and the second ball dropper assembly operable to retain and release ball 141.

Whether by ball 140 or ball 141, once packer assembly 132 has been set, additional pressure within flow path 122 may be used to cause ball 140 or ball 141 to pass through ball seat 136 as well as ball seat 128 in ball seat assembly 126, which requires a larger ball than ball 140 or ball 141, in the illustrated embodiment. Alternatively, return flow may be used to retrieve ball 140 or ball 141 to the surface or other secure location. Thereafter, as best seen in FIG. 2D, ball 148 may be deployed from ball dropper assembly 146 to ball seat 128. Ball 148 is released from ball dropper assembly 146 responsive to operation of actuator 150. Actuator 150 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. The deployment signal causes actuation of actuator 150, which in turn causes release of ball 148 into flow path 122. Gravity, fluid flow or a combination thereof, then causes ball 148 to travel downhole and engage ball seat 128 of ball seat assembly 126. In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen 124 and perforations 118 through cross over assembly 130. Thereafter, additional pressure within flow path 122 may be used to cause ball 148 to pass through ball seat 128 or return flow may be used to retrieve ball 148 to the surface or other secure location.

During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor 152 of ball dropper assembly 146 is operable to determine whether ball dropper assembly 146 has released ball 148 into flow path 122. Sensor 152 may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball 148 is located within ball dropper assembly 146, whether ball 148 has passed through a particular location of ball dropper assembly 146, whether ball 148 has passed through a particular location in flow path 122 or combinations thereof. Regardless of the sensing means, if sensor 152 determines that ball 148 has been released into flow path 122, sensor 152 is operable to provide a signal that indicates ball 148 has been released into flow path 122. Depending upon the configuration of tool string 112, this signal may be sent to the surface, sent to another downhole tool or, as illustrated, the signal can be processed by ball dropper assembly 146 to deactivate the portion of ball dropper assembly 146 responsible for release of ball 149 into flow path 122. In this manner, proper deployment of ball 148 into flow path 122 prevents a subsequent unwanted deployment of ball 149 into flow path 122.

During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor 152 is operable to determine whether ball 148 has been deployed from ball dropper assembly 146 into flow path 122. In the event that sensor 152 determines that ball 148 has not been deployed from ball dropper assembly 146 into flow path 122, the present disclosure includes a second and redundant ball; namely ball 149 in ball dropper assembly 146 that is operable for use in actuating downhole tools such as cross over assembly 130. In this case, ball 149 is released from ball dropper assembly 146 responsive to operation of actuator 151. Actuator 151 may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator 151 and the required actuation signal for actuator 151 are different from actuator 150 and the required actuation signal for actuator 150. This is preferred as the cause of the failure of deployment of ball 148 may also cause a failure of deployment of ball 149 if the same type of actuator and same type of actuation signal are used.

If it is determine that ball 148 has not been deployed from ball dropper assembly 146 into flow path 122 by sensor 152, then ball dropper assembly 146 is sent a deployment signal and ball 149 is deployed from ball dropper assembly 146 into flow path 122 (not pictured). Gravity, fluid flow or a combination thereof, then causes ball 149 to travel downhole and engage ball seat 128 of ball seat assembly 126. In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen 124 and perforations 118 through cross over assembly 130. Thereafter, additional pressure within flow path 122 may be used to cause ball 149 to pass through ball seat 128 or return flow may be used to retrieve ball 149 to the surface or other secure location. It is noted that ball dropper assembly 146 could have one or more additional and redundant balls which could be deployed into flow path 122 in a manner similar to that of ball 149. In addition, it is noted that tool string 112 could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path 122 in a manner similar to that of ball 149.

Referring next to FIG. 3, a process flow diagram generally designated 200, depicts a method for actuating a downhole tool using a downhole ball dropping system according to an embodiment of the present disclosure. The process begins by positioning the downhole ball dropping system in a well at step 202. Once properly positioned in the well and it is desired to operate a downhole tool that requires ball interaction, a deployment signal is sent to actuate an actuator to cause release of a ball by a ball dropper assembly into the flow path at step 204. The deployment signal may be a sent from a surface controller or may be generated downhole as described above. One or more sensors then determine whether a ball has been properly deployed in decision 206. If the sensor determines that a ball has been properly deployed, the sensor generates one or more deactivation signals to prevent release of any redundant balls from a ball dropper assembly into the flow path in step 208. The deactivation signals may be sent directly to the appropriate ball dropper assembly or assemblies and may alternatively or additionally be sent to the surface controller. If the deactivation signal is first sent to the surface controller, the well operator may acknowledge the received signal and then send one or more deactivation signals to the appropriate ball dropper assembly or assemblies as required. The process then progresses to actuating the downhole tool with the deployed ball in step 210. If in decision 206 the sensor determines that a ball has not been properly deployed, the sensor generates a signal indicative of this failure, which is preferably sent to the surface controller where it is determined whether a redundant ball is available in a ball dropper assembly in decision 212. If the failure signal is sent to the surface controller, the well operator may acknowledge the received signal before moving to the next step. If no redundant ball is available, the process ends. If a redundant ball is available, a signal is sent, for example from the surface controller, to actuate an actuator to cause release of a redundant ball from a ball dropper assembly into the flow path at step 214. The process then returns to decision 206 to determine whether a ball has been properly deployed and a single indicating whether the ball has been deployed may be sent to the surface controller. The process can continue until either, a redundant ball is properly deployed, a deactivation signal is sent and the downhole tool is actuated or no redundant balls are available.

Referring next to FIGS. 4A-4M, therein are depicted schematic illustrations of various actuators that are operable for use in the downhole ball dropper assemblies of the present disclosure. In FIG. 4A, actuator 300 includes an outer housing 302 and an inner sleeve 304 having a ball release opening 306. Outer housing 302 and inner sleeve 304 are initially secured together with a shearable member depicted as shear screw 308 Inner sleeve 304 is threadably coupled to a lower connector 310. In the illustrated embodiment, a cylindrical region 312 is formed between outer housing 302 and inner sleeve 304. A ball ramp 314 is sealably positioned in cylindrical region 312 and is preferably secured to outer housing 302. Ball ramp 314 includes a fluid passageway 316 having a metering valve circuit 318 positioned therein. A fluid chamber 320 is defined between the lower end of ball ramp 314, outer housing 302 and inner sleeve 304. A viscous fluid such as oil is contained within fluid chamber 320. In addition, a return spring 322 is positioned within fluid chamber 320. A mandrel 324 is securably coupled to outer housing 302. Mandel 324 includes a spring loaded ball support member 326. A ball 328 is initially coupled to ball support 326 by a magnetic coupling, a shearable member or the like. One or more sensors 330 are located in proximity to ball 328 and are operable to provide a signal that indicates ball 328 has or has not been released into the flow path as described above.

In operation, actuator 300 releases ball 328 responsive to a mechanical deployment signal. Specifically, when the tool string including actuator 300 is positioned in the well and it is desired to deploy ball 328 into the flow path of the tool string, weight is applied on mandrel 324. When sufficient shear force is generated between outer housing 302 and inner sleeve 304, shear screw 308 is broken. Thereafter, the outer housing 302, ball ramp 314 and mandrel 324 are shiftable relative to inner sleeve 304. The downward force on mandrel 304 now compresses spring 322 and is counteracted by the fluid moving through metering valve circuit 318 to require a predetermined amount of time for this operation. As outer housing 302, ball ramp 314 and mandrel 324 move downwardly relative to inner sleeve 304, ball 328 becomes aligned with ball release opening 306 of inner sleeve 304 and ball 328 is released from ball support member 326, through ball release opening 306 and into the flow path of the tool string. After deployment of ball 328, release of weight on mandrel 324 allows spring 322 to return outer housing 302, ball ramp 314 and mandrel 324 substantially to their run in positions.

In FIG. 4B, actuator 330 includes an outer housing 332 and an inner sleeve 334 having a ball release opening 336. Outer housing 332 includes a fluid passageway 338 that is in fluid communication with the annulus when actuator 300 is positioned in the well. Outer housing 302 is threadably coupled to a lower connector 340. In the illustrated embodiment, a cylindrical region 342 is formed between outer housing 332 and inner sleeve 334. A ball ramp 344 is positioned in a lower portion of cylindrical region 342 and a ball release assembly 346 is positioned in an upper portion of cylindrical region 342. Ball release assembly 346 has a cylindrical chamber 348 that is in fluid communication with fluid passageway 338. A piston 350 is sealably disposed within cylindrical chamber 348 and is initially secured therein with a shearable member depicted as shear screw 352. Below piston 350, cylindrical chamber 348 contains a viscous fluid such as oil 354. A fluid flow control element depicted as orifice 356 is positioned between oil 354 and a piston 358. The lower end of piston 358 is proximate to or in contact with ball 360, which is held in place by a resilient ball holder 362. One or more sensors 364 are located in proximity to ball 360 and are operable to provide a signal that indicates ball 360 has or has not been released into the flow path as described above.

In operation, actuator 330 releases ball 360 responsive to a pressure deployment signal. Specifically, when the tool string including actuator 330 is positioned in the well and it is desired to deploy ball 360 into the flow path of the tool string, annulus pressure is increased to apply a downward force on piston 350. When sufficient shear force is generated between piston 350 and ball release assembly 346, shear screw 352 is broken. Thereafter, the piston 350 is shiftable relative to ball release assembly 346. The downward force on piston 350 is counteracted by fluid 354 moving through orifice 356 to require a predetermined amount of time for this operation. As piston 350 moves downwardly, fluid 354 acts on piston 358, which shifts piston 358 downwardly pushing ball 360 out of ball holder 362. Ball 360 then contacts ball ramp 344 which is aligned with ball release opening 336 enabling ball 360 to enter the flow path of the tool string. It is noted that the pressure deployment signal could alternatively be generated by increasing the tubing pressure by porting cylindrical chamber 348 to the tubing side.

In FIG. 4C, actuator 400 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404. Cylindrical chamber 430 is in fluid communication with a fluid passageway 434 that is ported to the annulus and a fluid passageway 436, which is ported to the flow path of the tool string. A piston 438 is sealably disposed within cylindrical chamber 430 and is initially secured therein with a shearable member depicted as shear screw 440. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above. For example, when ball release assembly 410 is operated such that lower ramp element 422 of plunger member 420 slides into slot 418 of ball ramp 412, this is an indication that ball 428 has been expelled into the tubing. The one or more sensors 442 may determine that the two parts have slide together, for example, by opening or closing an electronic circuit, by cutting an electrical wire or breaking an optical fiber, by actuating a pressure switch, by aligning a magnet with a Hall Sensor or the like. The signal that indicates whether ball 428 has or has not been released into the flow path may be sent to a surface control by a wellbore communication means including, but not limited to, a electric conductor, an optical fiber, acoustic or electromagnetic telemetry or other suitable means. Actuator 400 may also include a lock assembly 444 that interacts with a locking feature 446 of piston 438 when piston 438 is fully extended.

In operation, actuator 400 releases ball 428 responsive to a differential pressure deployment signal. Specifically, when the tool string including actuator 400 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, tubing pressure is increased to generate a differential pressure between the tubing pressure and the annulus pressure which applies a downward force on piston 438. When sufficient shear force is generated, shear screw 440 is broken. Thereafter, piston 438 is shiftable relative to outer housing 402 and the downward force on piston 438 acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 may be fully extended such that locking feature 446 interacts with lock assembly 444 preventing retraction of piston 438. In this configuration, ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 400 from abrasive fluid flow.

In FIG. 4D, actuator 450 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 436, which is ported to the flow path of the tool string. A piston 438 is sealably disposed within cylindrical chamber 430. A rupture disk 452 is also disposed within cylindrical chamber 430 between fluid passageway 436 and piston 438. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, actuator 450 releases ball 428 responsive to a pressure deployment signal. Specifically, when the tool string including actuator 450 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, tubing pressure is increased which acts on rupture disk 452. When the tubing pressure reaches a sufficient absolute pressure, rupture disk 452 will burst. Thereafter, the fluid pressure generates a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 450 from abrasive fluid flow.

In FIG. 4E, actuator 460 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 434, which is ported to the annulus. A piston 438 is sealably disposed within cylindrical chamber 430. A lock assembly 462 is also disposed within cylindrical chamber 430. Lock assembly 462 includes a lock ring 464, a piston 466 and a retainer member 468. Initially, movement of piston 466 and lock ring 464 is prevented by the secure connection between piston 466 and retainer member 468 depicted as a shear screw 470. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, actuator 460 releases ball 428 responsive to a pressure deployment signal. Specifically, when the tool string including actuator 460 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, annulus pressure is increased which acts on piston 466. When sufficient shear force is generated, shear screw 470 is broken allowing piston 466 to shift upwardly releasing lock ring 464. Thereafter, the fluid pressure generates a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 460 from abrasive fluid flow.

In FIG. 4F, actuator 480 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404. Cylindrical chamber 430 is in fluid communication with a fluid passageway 434 that is ported to the annulus and a fluid passageway 436, which is ported to the flow path of the tool string. A dual piston assembly 482 is sealably disposed within cylindrical chamber 430. Dual piston assembly 482 includes a lower piston 484 that has an outer surface operable to cooperate with ratchet keys 486 to allow relative downward movement of lower piston 484 but prevent relative upward movement of lower piston 484. Dual piston assembly 482 also includes an upper piston 488 that has an outer surface operable to cooperate with ratchet keys 490 to allow relative upward movement of lower piston 488 but prevent relative downward movement of lower piston 488. A biasing member depicted as a spiral wound compression spring 492 is positioned between upper piston 488 and a lock ring 494 that is secured within cylindrical chamber 430. Spring 492 acts to separate upper piston 488 from lower piston 484. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, actuator 480 releases ball 428 responsive to a pressure deployment signal. Specifically, when the tool string including actuator 480 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, tubing pressure is increased which acts upper piston 488 compressing spring 492. Downward movement of upper piston 488 downwardly shifts lower piston 484 downwardly via ratchet keys 490. At the same time, lower piston 484 is able to move downwardly relative to ratchet keys 486. When tubing pressure is released, the biasing force of spring 492 either alone or in combination with the fluid pressure force of the annular fluid via fluid passageway 434 acts to upwardly shift upper piston 488 which is able to move upwardly relative to ratchet keys 490. At the same time, ratchet keys 486 prevent upward movement of lower piston 484. The tubing pressure is then cycled up and down in a manner similar to that described above to further downwardly shift lower piston 484 in a stepwise fashion. This process continues as lower piston 484 and inner sleeve 404 move together and spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, further downward movement of inner sleeve 404 positions ball release opening 406 behind a lower portion of outer housing 402 to protect the inside components of actuator 480 from abrasive fluid flow.

In FIG. 4G, actuator 500 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420.

Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. An upper portion of cylindrical chamber 430 is in fluid communication with a fluid passageway 434, which is ported to the annulus. A piston 438 is sealably disposed within cylindrical chamber 430. A computer controlled lock assembly 502 is also disposed within cylindrical chamber 430. Computer controlled lock assembly 502 may include a self contained power source such as one or more batteries, a processor, memory, instructions and a motor having a retractable arm with a lock ring 504 attached thereto. Computer controlled lock assembly 502 may receive external stimuli from one or more sensors 506, 508 such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, depending upon the configuration of computer controlled lock assembly 502, actuator 500 releases ball 428 responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. For example, a pressure deployment signal may be detected by sensor 506, sensor 508 or both. Alternatively or additionally, an acoustic deployment signal or a temperature deployment signal could be detected by sensor 506, sensor 508 or both. As yet another alternative, an accelerometer and timer may work together to generate a deployment signal based upon actuator 500 remaining stationary for a predetermined time period. This deployment signal may be in addition to one of the exterior stimuli, i.e., pressure, temperature, acoustic, discussed above. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled lock assembly 502 verifies the deployment signal then triggers the motor to retract its arm along with lock ring 504 to release piston 438. Thereafter, annular fluid pressure via fluid passageway 434 generates a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 500 from abrasive fluid flow.

In FIG. 4H, actuator 510 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. A piston 438 is sealably disposed within cylindrical chamber 430. A motor 512 having an extendable shaft 514 is also disposed within cylindrical chamber 430. In the illustrated embodiment, motor 512 receives power and command signals via communication cable 516 including one or more electrical conductors and one or more optional optical conductors communicably linked to a surface controller or other downhole controller. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, actuator 510 releases ball 428 responsive to one or more of an optical and an electrical deployment signal. Specifically, when the tool string including actuator 510 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, the surface controller sends the deployment signal and provides power to operate motor 512. In the illustrated embodiment, the motor drives the extendable shaft 514 downward generating a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, further downward movement of inner sleeve 404 positions ball release opening 406 behind a lower portion of outer housing 402 to protect the inside components of actuator 510 from abrasive fluid flow.

In FIG. 41, actuator 520 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 434, which is ported to the annulus. A piston 438 is sealably disposed within cylindrical chamber 430. A computer controlled release assembly 522 is also disposed within cylindrical chamber 430. Computer controlled release assembly 522 may include a self contained power source such as one or more batteries, a processor, memory, instructions and a motor having a retractable arm 524 that is sealable received within cylindrical chamber 430. Computer controlled release assembly 502 may receive external stimuli from one or more sensors 526 such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, depending upon the configuration of computer controlled release assembly 522, actuator 520 releases ball 428 responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly 522 verifies the deployment signal then triggers the motor to retract arm 524 which exposes cylindrical chamber 430 to annular pressure generating a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 520 from abrasive fluid flow.

In FIG. 4J, actuator 530 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420.

Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 434, which is ported to the annulus. A piston 438 is sealably disposed within cylindrical chamber 430. A computer controlled release assembly 532 is also disposed within cylindrical chamber 430. Computer controlled release assembly 532 may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly 532 is operably coupled to a disappearing plug 534 disposed in fluid passageway 434 via wire 536. Computer controlled release assembly 532 may receive external stimuli from one or more sensors 538 such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, depending upon the configuration of computer controlled release assembly 532, actuator 530 releases ball 428 responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly 532 verifies the deployment signal then triggers a current flow to generate heat in wire 536 which melts or otherwise removes plug 534 and exposes cylindrical chamber 430 to annular pressure generating a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 530 from abrasive fluid flow.

In FIG. 4K, actuator 540 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 436, which is ported to the flow path of the tool string. A piston 438 is sealably disposed within cylindrical chamber 430. A computer controlled release assembly 542 is also disposed within cylindrical chamber 430. Computer controlled release assembly 542 may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly 542 is operably coupled to a disappearing plug 544 disposed in an orifice 546 via wire 548. Computer controlled release assembly 542 may receive external stimuli from one or more sensors 550 such as pressure sensors, temperature sensors, hydrophones or the like. Also disposed within cylindrical chamber 430 is a piston 552. A viscous fluid 554, such as oil, is disposed between piston 552 and orifice 546. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, depending upon the configuration of computer controlled release assembly 542, actuator 540 releases ball 428 responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly 542 verifies the deployment signal then triggers a current flow to generate heat in wire 548 which melts or otherwise removes plug 544. Tubing pressure via fluid passageway 436 acts on piston 552 to move piston 552 downwardly. The downward force on piston 552 is counteracted by fluid 554 moving through orifice 546 to require a predetermined amount of time for this operation. After passing through orifice 546, fluid 554 acts on piston 438, which in turn acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 540 from abrasive fluid flow.

In FIG. 4L, actuator 560 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404. A piston 438 is sealably disposed within cylindrical chamber 430. A computer controlled release assembly 562 is also disposed within cylindrical chamber 430. Computer controlled release assembly 562 may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly 562 is operably coupled to a fluid pump 564. A fluid passageway 566 extends through outer housing 402 connecting a lower portion of cylindrical chamber 430 with an inlet of fluid pump 564. A fluid 568 is disposed within cylindrical chamber 430 and is operably to be pumped therein. Computer controlled release assembly 562 may receive external stimuli from one or more sensors 570 such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, depending upon the configuration of computer controlled release assembly 562, actuator 560 releases ball 428 responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly 562 verifies the deployment signal then triggers operation of fluid pump 564 which circulates fluid through cylindrical chamber 430 creating a high pressure regions above and a low pressure region below piston 438. This action generates a downward force on piston 438, which acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, further downward movement of inner sleeve 404 positions ball release opening 406 behind a lower portion of outer housing 402 to protect the inside components of actuator 560 from abrasive fluid flow.

In FIG. 4M, actuator 580 includes an outer housing 402 and an inner sleeve 404 having a ball release opening 406. In the illustrated embodiment, inner sleeve 404 is slidably disposed within outer housing 402. A lower cylindrical chamber 408 is defined between inner sleeve 404 and outer housing 402. A ball release assembly 410 is positioned in cylindrical chamber 408. Ball release assembly 410 includes a ball ramp 412 having a pair of ramp members 414, 416 with a slot 418 therebetween, as best seen in FIG. 5. Ball release assembly 410 also includes a plunger member 420 having a lower ramp element 422 that is operable to enter slot 418 of ball ramp 412. Ball release assembly 410 further includes a biasing member depicted as spiral wound compression spring 424 that is disposed around an upper extension 426 of plunger member 420. In certain embodiments, plunger member 420 may optionally be secured to outer housing 402 in the run in configuration. A ball 428 is positioned within cylindrical chamber 408 between ball ramp 412 and plunger member 420. Ball 428 may initially be secured to ball ramp 412 and/or plunger member 420 magnetically, shearably or the like. Outer housing 402 includes a cylindrical chamber 430 located above an upper surface of platform 432 of inner sleeve 404, the lower portion of which is an atmospheric chamber 448. Cylindrical chamber 430 is in fluid communication with a fluid passageway 436, which is ported to the flow path of the tool string. A piston 438 is sealably disposed within cylindrical chamber 430. An electromagnet 582 is also disposed within cylindrical chamber 430. Electromagnet 582 is powered via wire 584, which is coupled to an electrical source located downhole or at the surface. Electromagnet 582 is operable to generate a magnetic field that acts on magneto-rheological fluid 586 to form a barrier within cylindrical chamber 430. Also disposed within cylindrical chamber 430 is a piston 588. One or more sensors 442 may be located in proximity to ball 428 and are operable to provide a signal that indicates ball 428 has or has not been released into the flow path as described above.

In operation, actuator 580 releases ball 428 responsive to an electrical deployment signal. Specifically, when the tool string including actuator 580 is positioned in the well and it is desired to deploy ball 428 into the flow path of the tool string, the electric power to electromagnet 582 is cut off. The magneto-rheological fluid 586 that previously formed a barrier not returns to its liquid state. Tubing pressure via fluid passageway 436 acts on piston 588 to move piston 588 downwardly causing fluid 586 to acts on piston 438 which in turn acts through inner sleeve 404 to compress spring 424. Now, piston 438 and inner sleeve 404 move together until spring 424 is fully compressed or a lower surface of platform 432 of inner sleeve 404 contacts upper extension 426 of plunger member 420. In this position, ball 428 is aligned with ball release opening 406. Further downward movement of piston 438 and inner sleeve 404 now causes plunger member 420 to shift downwardly relative to ball ramp 412. The combination of the downward movement of piston 438 and inner sleeve 404 together with the force generated by spring 424 between ball ramp 412 and plunger member 420 cause ball 428 to be expelled through ball release opening 406 and into the flow path of the tool string. After deployment of ball 428, piston 438 preferably remains in its fully extended positioned wherein ball release opening 406 has moved behind a lower portion of outer housing 402 to protect the inside components of actuator 580 from abrasive fluid flow.

It should be understood by those skilled in the art that the illustrative embodiments described herein are not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to this disclosure. It is, therefore, intended that the appended claims encompass any such modifications or embodiments. 

What is claimed is:
 1. A downhole ball dropping system operable to be positioned in a well, the system comprising: a tool string having a flow path; a first ball dropper assembly interconnected in the tool string, the first ball dropper assembly releasably retaining a first ball; a second ball dropper assembly interconnected in the tool string, the second ball dropper assembly releasably retaining a second ball; and a sensor operable to detect deployment of the first ball and operable to generate a signal to prevent release of the second ball from the second ball dropper assembly.
 2. The downhole ball dropping system as recited in claim 1 wherein the second ball dropper assembly is positioned downhole of the first ball dropper assembly.
 3. The downhole ball dropping system as recited in claim 1 wherein the second ball dropper assembly is circumferentially positioned relative to the first ball dropper assembly.
 4. The downhole ball dropping system as recited in claim 1 wherein the sensor is operable to detect the first ball passing through the flow path after release thereof by the first ball dropper assembly.
 5. The downhole ball dropping system as recited in claim 4 wherein the first ball further comprises a magnetic device and wherein the sensor detects a change in a magnetic field.
 6. The downhole ball dropping system as recited in claim 4 wherein the first ball further comprises an RFID tag and wherein the sensor further comprises an RFID reader.
 7. The downhole ball dropping system as recited in claim 1 wherein the sensor is operable to detect release of the first ball from first ball dropper assembly.
 8. A downhole ball dropping method comprising: positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal to the first ball dropper assembly to release the first ball; detecting deployment of the first ball with a downhole sensor; and generating a deactivation signal from the downhole sensor to prevent release of the second ball from the second ball dropper assembly.
 9. The downhole ball dropping method as recited in claim 8 wherein sending the deployment signal to the first ball dropper assembly to release the first ball further comprises sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof.
 10. The downhole ball dropping method as recited in claim 8 wherein detecting deployment of the first ball with the downhole sensor further comprises detecting the first ball passing through the flow path after release thereof by the first ball dropper assembly.
 11. The downhole ball dropping method as recited in claim 10 wherein detecting the first ball passing through the flow path after release thereof by the first ball dropper assembly further comprises detecting a change in a magnetic field.
 12. The downhole ball dropping method as recited in claim 10 wherein detecting the first ball passing through the flow path after release thereof by the first ball dropper assembly further comprises detecting an RFID tag.
 13. The downhole ball dropping method as recited in claim 8 wherein detecting deployment of the first ball with the downhole sensor further comprises detecting release of the first ball from first ball dropper assembly.
 14. A downhole ball dropping system operable to be positioned in a well, the system comprising: a tool string having a flow path; a first ball dropper assembly interconnected in the tool string, the first ball dropper assembly releasably retaining a first ball; a first actuation assembly operably associated with the first ball dropper assembly, the first actuation assembly operated responsive to a deployment signal of a first type; a second ball dropper assembly interconnected in the tool string, the second ball dropper assembly releasably retaining a second ball; and a second actuation assembly operably associated with the second ball dropper assembly, the second actuation assembly operated responsive to a deployment signal of a second type, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability.
 15. The downhole ball dropping system as recited in claim 14 wherein the second ball dropper assembly is positioned downhole of the first ball dropper assembly.
 16. The downhole ball dropping system as recited in claim 14 wherein the second ball dropper assembly is circumferentially positioned relative to the first ball dropper assembly.
 17. The downhole ball dropping system as recited in claim 14 wherein the deployment signal of the first type and the deployment signal of the second type are each selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof
 18. A downhole ball dropping method comprising: positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal of a first type to the first ball dropper assembly to release the first ball; determining deployment of the first ball failed; and sending a deployment signal of a second type to the second ball dropper assembly to release the second ball, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability.
 19. The downhole ball dropping method as recited in claim 18 wherein determining deployment of the first ball failed further comprises determining deployment of the first ball failed with a downhole sensor.
 20. The downhole ball dropping method as recited in claim 18 wherein sending the deployment signal of the first type and sending the deployment signal of the second type each further comprises sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof 